This invention relates to a dock leveler, and more particularly to a dock leveler having a ramp movable to a raised position by inflation of an inflatable member disposed below the ramp.
In accordance with known construction, a dock leveler typically includes a ramp for bridging the space between a loading dock and the bed of a truck or other carrier parked adjacent the loading dock. The ramp is movable between a horizontal rest position and an inclined raised position. A lip is mounted to the outer end of the ramp, and is disposed in a pendant inoperative position when the ramp is in its rest position. After the ramp is moved to its raised position, the lip is moved to an extended position and engages the truck bed upon subsequent downward movement of the ramp to support the outer end of the ramp.
Recent developments in dock leveler technology have involved utilizing an inflatable member, such as an airbag, to lift the ramp to its raised position. Copending U.S. patent application Ser. Nos. 08/131,981 filed Oct. 4, 1993 and 08/131,983 filed Oct. 4, 1993, disclose dock levelers of this type, and the disclosures of these applications are hereby incorporated by reference.
The inflatable member or airbag is inflated using an inflating device, which can be any source of pressurized air. In one form, a fan or blower is mounted to the airbag support or to the ramp, and supplies low-pressure air to the interior of the airbag assembly to inflate the airbag assembly and to raise the ramp. As can be appreciated, when the fan or blower is operated, it has in the past been necessary to supply a sufficient quantity of air to the interior of the airbag assembly to completely occupy the entire volume defined by the interior of the airbag assembly in order to introduce sufficient pressure to the air to raise the ramp. This required the fan or blower to operate for several seconds without any movement whatsoever of the ramp, before the airbag assembly was filled with a sufficient quantity of pressurized air to commence lifting of the ramp.
In addition, the airbag assembly is typically constructed such that, when pressurized air is removed from the interior of the airbag assembly, the airbag assembly moves to a collapsed position under its own weight. This created a space below the ramp between the upper surface of the airbag assembly and the underside of the ramp. This space could collect debris or other objects, creating the potential for puncturing the airbag upon inflation of the airbag and engagement with the underside of the ramp.
It is an object of the present invention to provide a means for expediting filling of the inflatable member of a dock leveler with air upon operation of an inflating device. It is a further object of the invention to provide such a means which does not affect the overall structure or construction of either the inflatable member or any other component of the dock leveler. A still further object of the invention is to provide a means for maintaining the inflatable member in engagement with the underside of the ramp in order to eliminate the space between the bag and the ramp in which debris or other objects can collect.
In accordance with the invention, a dock leveler assembly includes a ramp movable to a raised position from a lowered position, an inflatable member located below the ramp, an inflating device interconnected with the inflatable member for introducing air into the interior of the inflatable member to raise the ramp, and a filler member located within the interior of the inflatable member. The filler member functions to maintain the inflatable member in a non-collapsed condition, in order to reduce the amount of air which must be introduced into the inflatable member in order to inflate the inflatable member and raise the ramp. The filler member may take any satisfactory form. In one embodiment, the filler member is constructed of a resilient foam material, which is placed into the interior of the inflatable member upon assembly of the inflatable member. The foam filler prevents the inflatable member from collapsing, thus, retaining air therewithin which would otherwise be exhausted if the inflatable member were to collapse. This functions to significantly reduce the volume of air which must be introduced into the inflatable member in order to raise the ramp. In an application where the inflatable member is not secured to the underside of the ramp, the filler member is constructed so as to maintain the upper portion of the inflatable member in contact with the underside of the ramp when the ramp is in its rest or operative position, in order to prevent debris or other objects from coming between the ramp and the inflatable member. In an arrangement in which the inflatable member has more than one chamber, a filler member is placed in each chamber of the inflatable member to prevent each member from collapsing and to prevent the upper portion of the inflatable member from blocking openings communicating between the chambers.
The invention further contemplates a method of expediting filling of an inflatable member in a dock leveler, or in any other assembly having a member which is movable to form one position to another in response to filling an inflatable member with air. The method of the invention is substantially in accordance with the foregoing summary.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.